Band sharpener



Feb. 4, 1969 H. c. sMMoNs ET AL BAND SHARPENER Sheet Filed May 19, 1966 /zzz/ //x/ 3, MM m v mm M m E I# w c s F 40 #a w Feb. 4, 1969 H. c. sMMoNs ET AL 3,425,l70` BAND SHARPENER Filed May 19, 1966 Sheet a I *KM 1969 H..SIMMONS ET AL 3425,170

BAND SHARPENER Filed May 19, 1966 Sheet- 3 of e ..PIE E INVENTORS /lk c S/MMoA/S &006405 k. 0041504/ Feb. 4, 1969 H. c s o s ET AL 3,425,170

BAND SHARPENER Sheet Filed May 19, 1966 H. c s o s ET AL 3,425,l70

F eb. 4, 1969 BAND SHARPENEH Filed May 19, 1966 Sheet FILE. E"

In a/zwaar Feb. 4, 1969 c.sMMoNs ET AL 3,425,17O

BAND SHARPENER Filed May 19, 1966 NVENTORS fidem( c'. s/Mavs 9006445 e MaMa-o ll'll lrrakvsys United States Patent ice 3,425,170 BAND SHARPENER Haryl 'C.`Simmons and Douglas R. Hanson, Anoka, Mnn.,

assignors to Gopher Grinders, Inc., Anoka, Minn., a

corporatio of Minnesota t Filed May 19, 1966, Ser. No. 551,441

U.S. CI. 51-247 Int. Cl. B24b 19/00 ABSTRACT OF THE DISCLOSURE This invention relates to an apparatus for sharpening an elongated moving member. More particularly the in` vention relates to an apparatus having a pairof sharpening units operable to sharpen cutting edges of endless bands of a bread slicing machine. r

Briefly described, the blade sharpening apparatus of this invention has an upper sharpening unit and a lower sharpening unit movably mounted on a support attached as a unit to the drive drum of a conventional bread slicing machine. The slicing machine has a plurality of endless cutting bands trained about the drive drum in side-by-side positions. Each band has a cutting edge which must be periodically sharpened to ensure eective slicing of bread.

Each sharpening unit has an abradingmember which rotates about an axis extended generally upright to the direction of 'movement of the bands. The abrading-members driven by separate motor means function to sharpen the cutting edges of the bands. The sharpening units are mounted on movable members operable to transport both sharpening units transversely of the bands. Asrthe sharp ening units travel transversely of the bands the abrading members consecutively move across the cutting edges sharpening both sides of each cutting edge.

A drive mechanism connected to the movable members supporting the sharpening units is operable toactuate the movable members for transporting both sharpening units at uniform speed transversely across consecutive bands. The operation of the drive mechanism is dictated by'a control system.- When the sharpening units have crossed all the bands the drive mechanism'is automatically reversed by the control system whereupon both sharpening units move back transversely across the bands to their initial starting positions. When the sharpening units are in their starting positions the control system of the drive mechanism is automatically shut off. As soon as the sharp'- ening units reach their starting positions the bread slicing 'machine is in condition for immediate use.

The blade sharpening apparatus of this invention can be mounted on conventional type bread slicing machines having a plurality of endless bands with a minimum'of time and efort. A' new band can be placed about the drive drum of the machine without disassembling the sharpening units or the support structure for the sharpening units. The sharpening apparatus has a safety arm which actuates a safety switch in the control system to open the power circuit of the control system. This safety switch is actu- .16 Claims line 6-6 of ,FIGURE Patented Feb. 4, 1969 ated by the arm when a new band or grinding wheel is placed on the machine. In the d'rawings: v FIGURE 1 isa side elevational view of a bread slicing, machine equipped with the blade sharpening apparatus 'of this invention; V

FIGURE`2 is an enlarged sectional view taken along line 2-2 of FIGURE 1; i FIGURE 3 is an enlarged 'sectional view takenalong line 3-3 of FIGURE 2; FIGURE 4` is an enlarged sectional view 'taken along line 4-4 of FIGURE 2; I I FIGURE 5 is an enlarged side view partly in section of one power driven grnding unit of the sharpening apparatus; a i FIGURE 6 is 'an enlarged sectional 'view taken along FIGURE 7 isla 'sectional view taken along the line 7 "7 of FIGURE 4 showing the abrading members engaging the cutting edges of the bands; v v. 'V

FIGURE 8 is an enlarged fragmentary sectional view taken along line 8-8 of FIGURE 7 showing an abrading.

, control system for the drive mechansm and the sharpening units of the apparatus of this invention; and

FIGURE 11 is a diagramma-tic view of the reversing switch for the drive motor "of the control system.

Referring to the drawingsthere is shown in FIGURE 1 a bread slicing machine indicated generally at 15. Machine 15 is a conventional bread slicing machine having a frame 16 which includes ar'gula-rly disposed pairs of side members 17 and 18. Transversely positioned between the bottom ends of side members 17 and 18 is a lower drive drum 19 mounted on stub axles 21 and ;22. As shown in FIGURE 2, stub axles 21 and 22 are threaded through supports 23 and 24 mounted, on the side members 17 and 18 respectively. The forward ends of axles 21 and 22 project into recesses in the end of a stationary shaft 25 ex- I tended axially through druni 19. Stub axles 21 and 22 are removable from shaft 25 to permit replacement of drum 19 and endless bands about the drum. Rotation of stub axles 21 and 22 is facilitated with the use of transverse rods 26 projected through suitable holes in the ends of the stub axles.

Referring to FIGURE 1, transversely located between the upper ends of the side members 17 and 18 is an upper drum 26 mounted in bearing blocks 27 adjustably carried on the upper ends of side members 17 and 18. Adjustable assemblies 28 are used to adjust and hold the longitudinal position of upper drum 26. A plurality of endless metal bands 29 are trained about the drums 19 and 26. The reaches or runs of each band between the drums are twisted 180 degrees so that the center sections of the reaches are substantially perpendicular to the planes of movement of the reaches. Bands 29 are aXially spaced on drums 19 and 26 with center sections of the reaches of the bands forming a transverse cutting zone. The forward cutting edges 30 of the bands provide a series of axially spaced cutting edges. Shown in FIGURE 8, cutting edge 30 of band 29 has a scalloped or sinusoidal shape. Rearwardly projected fingers 31 and 32 are used to space and vertically align the center sections of the reaches of endless bands 29 from each other. Guides 31 and 32 are located between tables 33 and 34 used to guide a loaf of bread 35 through the cutting zone of the machine.

Lower drive drum 19 is driven by an electric motor 36 mounted on frame 16. Power is transmitted from motor 36 to drum 19 by an endless belt drive 37 trained about one end of drum 19 and the drive pulley of the motor. In use the rotating drum 19 moves endless bands 29 at a rate of speed of approximately 1200 feet per minute. Over a period of use cutting edges 30 of the endless bands become dull and must periodically be sharpened to provide effective and rapid cutting of the bread.

v The sharpening apparatus indicated generally at 38 is operable to automatically sharpen cutting edges 30 of each band. sharpening apparatus 38 is a self contained assembly mounted on machine 11 adjacent drum 19. The apparatus can be mounted on any conventional two drum bread slicing machine with a minimum of time and labor. sharpening apparatus 38 has sharpening units, as indicatedgenerally at 39 and 41, which move along transverse axes extended generally parallel to the axis of rotation of drum 19. sharpening units 39 and 41 are operable to sharpen the upper and lower surfaces of the cutting edges on the forward portion of the endless bands. As sharpening units 39 and 41 move transversely along their respective axes they sequentially sharpen the cutting edges on adjacent bands. The sharpening 'units move at a relatively slow rate of speed so that the entire cutting edge of each moving band is sharpened.

sharpening units 39 and 41 are movably mounted on a support indicated generally at 42 secured to opposite ends of the drum shaft 25 and extended transversely of the drum. Support 42 guides the sharpening units 39 and 41 for movements in directions transverse to the direction of movement of bands 29 and carries the sharpening units in unison sequentially across the bands.

Support 42 comprses arms 43 and 44 located opposite the ends of drum 19. Clamps 46 and 47 secure the arms to the opposite ends of the stationary shaft 25 extended through drive drum 19. Arms 43 and 44 are otfset outwardly away from the drum and project upwardly. They are used as supports for a transversely extended first movable member 48, as a worm or rod having a screw thread. Bearings 49 and 51 rotatably mount the opposite ends of member 48 on the arms 43 and 44, respectively. As shown in FIGURES 2 and 3, member 48 extends substantially parallel to the axis of rotation of drum 19 and is located between the upper and lower reaches or runs of endless bands 29. Positioned below and extended substantially parallel to member 48 is a guide rod 52 carried by adjustable support members 53 and 54, as nut and eye bolt assembles. Ears 56 and 57 having holes to accommodate support members 53 and 54 are secured to arms 43 and 44.

A second movable member 58, as a worm, extends transversely across the upper reaches or runs of endless bands 29. Member 58 is' substantially parallel to the axis of rotation of drum 19. As shown in FIGURE 5, the right end of member 58 projects through a hearing 59 mounted on upright member 60. The lower end of member 60 is secured to top side of arm 44. As shown in FIGURE 3, the opposite end of member 58 is rotatably mounted in a bearing 61 secured to an upright plate 62. Clamp unit 63 secured to the side of frame 18 supports plate 62. Located below and forwardly of member 58 is a top guide rod 64 carried in adjustable support members 66 and 67 in a manner similar to the nut and eye bolt assemblies forming support members 53 and 54.

A safety bar 68 extends from clamp unit 63 to the upper portion of arm 43. The upper end of bar 68 is pivotally mounted on a block 69 secured to plate 62. The upper end of bar 68 is engageable with an actuator of an on-off safety switch 71 mounted on top of plate 62. The opposite end of bar 68 is attached to arm 43 with a thumb screw 72 which is removable to allow angular movement of bar 68. As shown in broken lines, bar 68 has been moved to a position where the switch 71 is actuated to the off position thereby opening the electrcal circuit of t e icer motor 36 and blade sharpening apparatus. This safety feature eliminates accidental starting of the blade sharpening apparatus and slicer bands 29 when new endless bands are placed on drive drum 19 or when abrading members are replaced in the sharpening apparatus.

Replacement of endless bands can be done without removing the sharpening apparatus from the bread slicing machine. To replace an endless band, safety bar 68 must be disconnected from arm 43 and stub axle 22 withdrawn from the end of the drum shaft 25 as shown in broken lines in FIGURE 2. The endless replacement band is placed over arm 43 locating the top run of the band between the bottom member 48 and top member 58.

The upper and lower sharpening units 39 and 41 are identical in structure with the upper sharpening unit 39 mounted on worm 58 and guided by .guide rod 64. Lower sharpening unit 41 is mounted on worm 48 and guided by lower guide rod 52.

The following detailed description is limited to sharpening unit 39 shown in FIGURES 5 and 6. The corresponding structure in sharpening unit 41 is indicated with same reference numeral having a sufiix A. A square block or nut 73 is threaded onto member 58 and supports a step plate 74 secured to the bottom of the block by bolts 76. Located adjacent the lower end of plate 74 is an upwardly drected step bracket 77 projected over and engageable with the top of guide rod 64. Bolt and nut assemblies 78 secure the bracket to plate 74. Interposed between bracket 77 and the top of plate 74 is a curved leaf spring 79 engaging the bottom of the guide rod 64. Spring 79 biases the plate in a downward direction toward endless bands 29.

An abrading member 81, as a grinding wheel or other means for removing met-al, located below plate 74 is mounted for rotation about an axis extended upwardly from the direction of blades 29. Abrading member 81 is carried on an upright shaft 82 rotatably mounted on the end of plate 74 and a cover 83 by a pair of bearings 84. An electric motor 86 mounted on plate 74 is connected with belt drive 87 located within cover 83 to drive shaft 82 of abrading member 81. Motor 86 may be replaced with an air driven motor operably connected to drive shaft 82. The position of abrading member 81 relative to bands 29 is maintained by guide rod 64. Spring 79 biases the forward portion of the abrading member down into engagement with the bands and provides the abrading member with limited floating movement. As shown in FIGURE 5, the flat cutting bottom surface 88 of abrading member 81 is angularly inclined with respect to the direction of movement of bands 29. This angle is preferably 7 degrees but may vary with different shaped abrading members.

Referring to FIGURE 4, there is shown a drive mechanism indicated generally at 89 for rotating the movable members 48 and 58 whereby the sharpening units 39 and 41 move transversely over moving bands 29 with the abrading members 81 and 81A moving in unison across the top and bottom sides of the cutting edges of the band 29. Drive mechanism 89 comprses an upright electric motor 90 having a rotor 91. A brake disc 91A is secured to the lower end of the rotor shaft and engages the bottom wall of the motor housing when the motor is de-energized. Disc 91A and motor housing function as a brake for the rotor. When the motor is energized rotor 91 shifts upwardly moving disc 91A away from motor housing. Motor 90 drives a speed reduction gear box 92 mounted on a bracket secured to support 93 projected. rearwardly from the upright member 60. Gear box 92 has an output shaft 94 carrying a sprocket 96. A screw and friction plug 97 provide a friction drive connection between sprocket 96 and shaft 94. This drive connection functions as a slip clutch to limit the amount of torque which may be applied to members 48 and 58. Power is transmitted from sprocket 96 t-o sprockets 98 and 99 mounted on the ends of members 48 and 58 respectively by a roller link chain 101 trained about sprockets 96, 98 and 99.

The direction of rotation of rotor 91 is controlled by limit switches 102 and 104 mounted on plate 62 and bracket` 95 respectively located on opposite sides of the support. Limit switch 102 mounted on bracket 95 has an actuator finger 103 projected in the path of movement of sbarpening unit 39. When sharpening unit 39 engages finger 103 units 39 and 41 and in the initial at rest position. Limit switch 104 mounted on plate 62 has an actuator finger 106 located in the path of movement of the sharpening unit 39. When sharpening unit 39 engages finger 106 units 39 and 41 have reached the end of theirorward movement. Limit switch 104 operates in conjunction with a reversing switch indicated generally at 107 in FIGURE to change the direction of rotation of the drive motor 90. This reverses the rotation of the members 48 aud 58 thereby driving sharpening units 39 and 41 back toward limit switch 102.

Referring to FIGURE 10, there is shown the electrical-mech'anical diagram of the drive -mechanism for members 48 and 58 and the electrical control system for motors 86 and 86A of the sharpenng units and reversing motor 90. A source of electric power 108 is connected to starting magnetc unit 109 of motor 36 used to drive drum 19. The electric energy for the control system of the sharpening apparatus is derived through magnetic unit 109 so that drive motor 36 will rotate drum 19 simultaneously !with supplying electrical energy to the sharpening unit motors 86 and 86A and reversing motor 90.

A safety fuse 111 is interposed in a line 112 connecting magnetic unit 109 to safety switch 71 which must be in the on position before electric current is supplied to manually operated starting switch 113. Lines 114 and 11 6, as longitudinal coiled cords, connect switch 113 to sharpener unit motors 86 and 86A, respectively. The circuits for motors 86 and 86A are completed by a line :117 connectin g the motors to magnetic unit 109. Reversing switch 107 is connected to limit switches 102 and 104 by lines 118 and 119. The circuit t hroughreversin g switch 107 is completed by a line 120 connecting the reversing switch to line 117. Switch 102 is connected to a line 112 by line 121 which by-passes switch 113 providing limit switch 102 with 'a live first contact held in the open position by sharpening unit 39. Limit switch 102 is a double acting switch having oppositely acting first and second contacts. Second contact works opposite to the first contact to connect line 11-8 to power line 122 when the first contact is beld open.

Reversing switch 107 shown in FIGURES 10 and 11 has a pair of angularly movable contacts 123 and 124 located between pairs of stationary contacts 125, 126 and 127, 128 connected by lines 129 to the field and armature windings of reversing drive motor 90.' A U-shaped frame 130 is used to pivotally mount the movable contacts 123 and 124 and support a pair of solenoids 131 and 132 operable to control the "on" and off positions of contacts 123 and ;124. "Line 118 is connected to solenoid 131 and line 119 is connected to solenoid 132. Movable contacts 123 and 124 are held in their alternate "on positions, as shown in FGURES 10 and ll, by a pair of inter-looking ngers133 and 134 which change operati ve lock positions on energization of the oppositely located solenoid.

In use, to sharpen the cutting edges 30 of bands 29 motor 36 must be running to rotate drum 19 thereby moving bands 29' in separate longitudinal paths. The sharpening apparatus is energized by closing starting switch 113 thereby connectin g the source of electric power to motors 86 and '86A and to reversing motor 90. With switch 113 closed limit switch 102 couples switch 1 13 to line 118 thereby energizing solenoid 131.

The pull of solenoid 131 releases lock fingers 133 and 134 and moves contacts 123 and 124 into engagement with stationary contacts 126 and 12 8 whereby drive motor is energized and transmits power through drive lin-k c'hain 101 to move members 48 and 58 which in turn move sharpening units 39 and 41 transversely across the top and bottom runs of bands 29. Motors 86 and 86A drive abrading members 81 and 81A about separate unright axes with the forward portions of the abrading members engagng the cutting edges 30 of adjacent bands.

Starting switch 11-3 is momentarily held in the on position until the sharpening units 39 and 41 move from the rest position allowing limit switch 102 to return to the on` position. When switoh 102 is in the on position starting switch 113 is bypassed and the second contact in switch 102 is open de-energizing solenoid 131. Lock fingers 133 and 134 hold the movable contacts 123' and 124 in engagement with fixed contacts 126 and 128 'whereby motor 90 drives members 48 and 58 moving the sharpenin g units 39 and 41 at a uniform rate of speed transversely across bands 29. The units 39 and 41 move at a relatively slow rate of speed so that the abrading members `81 and `81A engage the entire length of the cuttingg edge of each band.

As shown in FIGURE 4, sharpening units 39 and 41 are angularly movable about the axes of members 48 and 58 and are biased by sprin gs 79 and 79A in a downward direction forcing the abrading members 81 and -81A into en-gagement with the cutting edges of one to three bands 29. The abrading bottom surfaces 88 and 88A of the abradin g members project in planes which intersect the moving bands at a small angle whereby the forward edges of the abrading members '81 and 81A are in abrasive contact with the cutting edges 30 of at least one band 29. The abradng members may contact a plnrality, as three, bands at the same time. As shown in FIGURE 8, the cutting surfaces of the abrading members move transversely across the cutting edge 30. This provides for self cleaning of the cutting surfaces 88 and 88A. As shown in FIGURES 1 and 7, bands 29 being in a figure 8 loop twist and turn from horizontal to vertical positions as they move in their paths and around drums 19 and 26. This exposes only the cutting edges 30 to the action of the abrading members. As the bands enter and leave drive drum 19 they are at a slight angle `with respect to tangents to the peripheral surface of the drum. With the bands at this angle the a'brading members engage only the scalped cutting edges 30 of the bands. The support 42 being attached to drum shaft 25 fixes the locations of the abradin g mernbers relative to the bands thereby eliminating adjustment of the apparatus on the machine to control the sharpening of the cutting edges of the bands.

As members 48 and 58 rotate sharpening units 39 and 41 move transversely of the direction of movement of bands 29. When the sharpening units have moved across the last band, unit 39 engages the reverse limit switch actuator finger 106 moving the finger from the "ofF' position to the on position whereby solenoid 132 is energized. The pull of solenoid 132 moves movable contacts 123 and 124 to engagement with opposite stationary contacts and 127 whereby electric motor 90 is reversed driving members 48 and 58 in reverse directions When this occurs sharpening units 39 and 41 move transversely back across bands 29 to complete the cycle. On reverse movement of the sharpening units the abrading members 81 and 81A engage the cutting edges of the bands. When the sharpening unit 39 engages actuator finger 103 of limit switch 102 motors 86, 86A and 90 are de-energized terminating power to members 48 and 58 as well as abrading members 81 and 81A.

As shown in FIGURE 4, when motor 90 is de-energized rotor 91 moves axially downward until dsc 91A engages the end of the motor housing to brake the transmission gear box 92. This braking action overcomes the momentum of the moving members 48 and 58 and chain 101. The brake prevents sharpening units 39 and 41 from moving beyond their at rest positions.

The invention has been described with reference to a preferred embodiment. It is to be understood that various omissions, substitutions, changes in the sharpening units and the drive mechanisms for the sharpening units may be made by those skilled in the art without departing from the spirit of the invention. The invention is defined in the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for sharpening a cutting edge of an elongated cutting member moving in the direction of the cutting edge comprising: a support having movable means extended transversely of the cutting member, a sharpening unit mounted on the movable means for movement transversely of the cutting member, said unit having a mountng member supporting the unit on the movable means, an arm secured to the mountng member, an abrading wheel rotatably mounted on the arm for rotation about an upright axis generally normal to the direction of movement of the cutting edge whereby an outer peripheral portion of the wheel engages the cutting edge and a motor mounted on the unit for rotating the wheel, said rotating wheel on movement of the movable means relative to the mountng member movable with the sharpening unit across the moving cutting edge of the elongated cutting member, and drive means for Operating said movable means for transversely moving said sharpening unit whereby a rotating outer peripheral portion of the wheel engages and moves transversely across the cutting edge.

2. The apparatus defined in claim 1 wherein said elongated cutting member is an endless band having a cutting edge along one side of the member.

3. The apparatus defined in claim 1 wherein naid movable means is a worm extended transversely of the cutting member and said mountng member comprises a member threaded on said worm, said drive means operable to rotate said worm whereby the sharpening unit moves parallel to the worm carrying the abrading wheel across the cutting edge.

4. The apparatus defined in claim 1 wherein the apparatus has a plurality of side by side endless bands, each band having a cutting edge, said abrading wheel engageable with at least one cutting edge and moving in sequence across each cutting edge.

5. The apparatus defined in claim 1 further characterized with control means for the drive means, said control means having reversing means operable to reverse the power transmitting direction of the drive means whereby the abrading wheel moves back transversely across the cutting edge.

6, The apparatus defined in claim 1 wherein said support includes guide means spaced from and extended parallel to said movable means, said sharpening unit having means cooperating with the guide means for biasing the abrading wheel toward the cutting member.

7. An apparatus for sharpening a plurality of knife bands trained around a pair of spaced rotating drums and twisted into a parallel relationship, each band having a cutting edge, a top run and a bottom run comprising: a support having a first movable means extended trans versely across the top runs of the bands and a second movable means extended transversely across the bottom runs of bands, said second movable means located between the top and bottom runs, a first sharpening unit mounted on the first movable means for movement transversely of the bands, a second sharpening unit mounted on the second movable means for movement transversely of the bands, each of said sharpening units having a mountng member supporting the sharpening unit on the associated movable means, an arm secured to the mountng member, an abrading wheel rotatably mounted on the arm for rotating about an upright axis generally normal to the direction of movement of the cutting edge whereby an outer peripheral portion of the wheel engages the cutting edge, and a motor mounted on the unit for rotating the wheel, said rotating wheel on movement of the movable means relative to the associated mountng member movable with the sharpening unit sequentially across each cutting edge of each band, and drive means for Operating said first and second movable means for transversely moving the first and second sharpening units whereby the rotating abrading wheel on the first sharpening unit sequentially engages and moves transversely across the cutting edges on the top runs of the bands and the rotating abrading wheel of the second sharpening unit sequentially engages and moves transversely across the cutting edges of the bottom runs of the bands.

8. The apparatus defined in claim 7 wherein one of said drums includes stationary means at opposte ends of the drums, said support having arms located adjacent the opposte ends of said one drum and means releasably securing the arms to said stationary means.

9. The apparatus defined in claim 7 wherein said first and second movable means are worms, said mountng members of said first and second sharpening unit each threaded on adjacent worms, said drive means operable to concurrently rotate said worms whereby the first and second sharpening units move transversely of the bands carrying the abrading wheels in sequence into engagement with and across the cutting edges of the bands.

10. The apparatus defined in claim 7 further characterized with control means for the drive means, said control means having reversing means operable to reverse the power transmitting direction of the drive means whereby the first and second sharpening units move back to their starting positions carrying the abrading wheels back transversely across the cutting edges of the bands.

11. The apparatus defined in claim 7 further characterized with control means for the drive means, said control means including a safety switch operable with a safety member which must be in a given location before safety switch allows energization of the control means.

12. The apparatus defined in claim 7 wherein said support means includes first and second transversely extended guide means positioned adjacent the first and second movable means respectively, each sharpening unit having means cooperating with the adjacent guide means for biasing the corresponding abrading wheels into engagement with the cutting edges of the bands.

13. The apparatus defined in claim 1 wherein said abrading wheel has a cutting surface positioned at an acute angle with respect to the plane of movement of the cutting member.

14. The apparatus defined in claim 7 wherein each abrading wheel has a cutting surface positioned at an acute angle with respect to the claimed movement of the cutting members.

15. An apparatus for sharpening a plurality of knife bands trained around a non-adjustable lower drum and an upper drum and twisted into parallel relationship, each band having a cutting edge comprising: a support having a movable means extended transversely of the knife bands, a sharpening unit mounted on the movable means for movement transversely across the knife bands, said unit having a mountng means supporting the unit on the movable member and an abrading wheel rotatably mounted for rotation about an uprght axis generally normal to the direction of movement of the cutting edges of the bands whereby an outer peripheral portion of the wheel engages the cutting edges of the bands, and a motor for rotating the wheel, said rotatng wheel on movement References Cited of the movable means relative to the mounting means UNITED STATES PATENTS moves sequentally across the cuttng edges of the bands, and drive means for Operating the movable means for 29973325 8/1961 Hansentransversely moving the sharpening unit whereby a ro- 2580778 1/1952 Heter et tating outer peripheral portion of the wheel sequentially 5 2391823 8/1961 Irvmen a s a d moves tr sversel acr th cutt' d es y OSS e mg e g FOREIGN PATENTS 16. The apparatus of claim 15 wherein the movable 860,092 2/ 1961 Great Britain.

means of the support extends substantially parallel and 10 adjacent to the non-adjustable lower drum. JAMES JONES, Prlmary Exammer- 

